Preparation and Characterization of CdSe Single Crystal

Abstract

High quality of CdSe single crystal is grown from the melt. X-ray fluorescence (XRF) showed that the ingot crystal has Cd:Se ratio very close to 1. The Photoresponse spectra in the energy range 1.2-2.1 eV is found to change with increasing temperature from 80 K to 300 K. At temperatures ≤ 200 K three peaks are observed at 1.45; 1.73 and 1.97 eV; whereas above 200 K, the peaks at 1.45 and 1.97 eV are washed out. These peaks are interpreted in terms of the band model, considering the band splitting. The photocurrent-temperature behaviour showed three main regimes: a weak dependence at lower temperatures; thermal quenching region (maximum at 200 K) and a marked decrease at higher temperatures. The onsets and offsets of the three regions are found to depend on the incident photon energy. A very high lifetime (milliseconds); being temperature dependent is obtained from the frequency resolved photoconductivity. The data are explained on the bases of recombination kinetics controlled by defect centres.